This invention relates to a heddle frame for a loom, and in particular to improved means in such heddle frames for preventing distortion with respect to the top and bottom rails of the frame and for simplifying the adjustment of the frame.
A known harness frame with a centerbrace is disclosed in U.S. Pat. No. 2,909,199. In this patent, the heddle frame comprises top and bottom rails which may be made of wood or extruded aluminum. The top and bottom rails are connected at each end by end struts to provide a rigid connection between the ends of the top and bottom rails to maintain the top and bottom rails at fixed distances apart.
The known heddle frame also includes top and bottom heddle supporting rods upon which the heddles are slidably mounted. The heddle rods are supported from the top and bottom rails by brackets or hooks. A stay or brace is mounted midway the ends of the frame and in some instances a plurality of braces may be employed where the width of the frame makes this desirable. The lower end of the brace is threaded in a member which is secured to the inner edge of the lower rail by wood screws. The upper end of the brace is also threaded into a headpiece which may be rectangular or other noncircular configuration. The headpiece is secured to the threaded upper end of the brace by means of a pin. The headpiece is seated into a recess of an upper locking member which is fastened by means of wood screws to the outer edge of the top rail of the frame. The upper end of the centerbrace is secured by a locking member which has a recess for the headpiece and which prevents rotation of the centerbrace when the locking member is in its operative position. The locking member is secured in the locking position by wood screws which pass into the top rail.
The harness frame of this patent offers support to the centerbrace but only in one predetermined location at or near the center of the frame. Furthermore, the use of the frame causes the centerbrace to move relative to the top and bottom rails resulting in undue wear.
Another well-known harness frame is an adjustable centerbrace as disclosed in U.S. Pat. No. 3,417,790. In this device, the adjustable centerbrace is extremely difficult to align in the harness frame and to correctly torque the holding screws which hold the centerbrace in place in the top and bottom rails. In this device, the final positioning of the centerbrace must be completed in the weaving machine after the warp has been drawn into the heddles with the warp and the top rails obstructing the view of the operator making the adjustment. This makes it very difficult to engage and to use the tools necessary to tighten the supports for the centerbrace. Furthermore, use of the tools within the presence of the warp threads results in damage to the warp threads during the installation of the center stays. This is a significant disadvantage.